Warp knitting machine

ABSTRACT

THE FRONT AND REAR THREAD TENSION &#34;SEESAWS,&#34; WHICH OPERATE WITH THE RESPECTIVE FRONT AND REAR SETS OF WARP THREADS OF A TWO-NEEDLE BED RASCHEL KNITTING MACHINE, ARE CONNECTED TOGETHER BY A TENSION SPRING SO THAT UNIFORM TENSION IS MAINTAINED ON EACH SET OF WARP THREADS DURING SWINGING MOVEMENTS OF THE THREAD GUIDES ACROSS THE NEEDLE BEDS. THIS TENSION SPRING CONNECTION PROVIDES TENSION COMPENSATION BETWEEN THE FRONT AND REAR SETS OF WARP THREADS BY CREATING A CONSTANT EXCHANGE OF KINETIC ENERGY BETWEEN THE RESPECTIVE TENSION SEESAWS WHILE THE LOADING OF THE SPRING REMAINS SUBSTANTIALLY UNCHANGED.

Jam 19 1971 I E WARP KNITTING MACHINE Filed May 5, 1969 INVENTOR. vMAmus ANTO1NE- PERRHi-R ATTORNEYS United States Patent 3,555,854 WARPKNITTING MACHINE Marius Antoine Perrier, Lyon, France, assignor to JeanGusken, Viersen-Dulken, Germany Filed May 5, 1969, Ser. No. 821,887Claims priority, application Germany, May 3, 1968, 1,760,324 Int. Cl.D04b 23/02 US. C]. 66-87 6 Claims ABSTRACT OF THE DISCLOSURE The frontand rear thread tension seesaws, which operate with the respective frontand rear sets of warp threads of a two-needle bed Raschel knittingmachine, are connected together by a tension spring so that uniformtension is maintained on each set of warp threads during swingingmovements of the thread guides across the needle beds. This tensionspring connection provides tension compensation between the front andrear sets of warp threads by creating a constant exchange of kineticenergy between the respective tension seesaws while the loading of thespring remains substantially unchanged.

The invention relates to an arrangement for maintaining uniform threadtension on two needle bed fiat warp knitting machines, especiallyRaschel machines, provided with at least two sets of warp threads guidedto the thread guides over spring weighted seesaws," and passingdownwardly on different sides of the thread-guide support shaft.

Incorporating of yarn tension seesaws in the feeding line of the sets ofthreads from the front and rear warp beams to the needles of the frontand rear beds becomes necessary because of the steadily changing yarnrequirements during the lay or shogging movements of the thread guidesand the insertion of the warp threads into the knitted fabric. Thethread tension seesaws, on which the sets of threads get an artificialelongation by each being directed under and over two thread tension rodsor tubes, are steadily compensating for the changing thread requirementsbecause the tension rods are pivotally mounted and are acting againstspring pressure. The seesaws make oscillating swinging movements througha limited angle under the counteracting loads of the thread tension onone side and the spring tension on the other side. If the limits of thisangle are exceeded to one or the other side, the speed of the warpthread feeding regulator has to be adjusted accordingly.

In certain applications the oscillating system, consisting of the massof the thread tension seesaw and the set of warp threads on one side andthe spring acting on the seesaw on the other side, can have aninsufficient dampening.

For instance, when knitting fine gauge hosiery type fabrics from veryfine thread or yarn on Raschel machines, it has been found thatinsufiicient dampening of the oscillating movements produces courses ofstitches which are uneven in their structure, which, of course, is notdesirable. On the other hand, the dampening cannot be artificiallyincreased due to the required easy movement of the yarn tension seesaws.

An object of the present invention is therefore to avoid thedisadvantage of an uneven stitch structure under all conditions andstill maintain an easy mobility of the yarn tension seesaws.

According to the invention, this problem is solved by providing atension spring connection between the yarn tension seesaws of the twosets of warp yarns which pass downwardly on opposite sides of the threadguide support shaft and whose warp threads are inserted into the knittedfabric with the same average yarn consumption.

The invention takes advantage of the condition that the oscillatingmovement of the guide supports carrying the yarn guides act in opposingdirections on the two sets of warp yarns, passing by on different sidesof the yarn guide support shaft. While the pull and the lengthrequirements increase on one set of yarns, the pull and lengthrequirements decrease on the other set of yarns and vice versa. This hasthe result that the respective yarn tension seesaws make counteractingmovements to compensate for the lengthening or shortening of the sets ofyarn so that there are at least overlapping motion componentscounteracting the oscillating movements. In known types of yarn tensioncompensation devices, the seesaw springs are suspended from the frameand have to continuously follow these movements so that their respectivemotion components and their potential energy changes continuously duringthis process. However, the spring loading of the yarn tension seesawsagainst each other, according to the invention, creates a system of twofunctionally connected masses having a constant exchange of kineticenergy between them, while the springitself changes its potential energyonly a little. Through this arrangement, as practical experience hasshown, the oscillating movements of the yarn tension seesaws areconsiderably smoother and a substantially more even stitch structureappears.

Elaborating on the invention in an advantageous way, a tension spring issuspended between two levers which are in turn connected to the two yarntension seesaws to thereby serve for the mutual spring loading of thetwo seesaws. The use of levers instead of a leather tape slung around apulley has the advantage that pre-tension force and tensioncharacteristics of the spring can be changed relatively easy and can beadapted to the operating requirements. To this end, the effective lengthof the levers can be adjustable and also the angles between the leversso that the operation of the yarn tension seesaws can be variable.

When the yarn tension control of the present invention is utilized on amachine provided with positive warp yarn feed, the two warp beamsbelonging to the mutually spring loaded yarn tension seesaws can bedriven by means of a joint yarn tension controlled and adjustablespecial gearing, whose adjustment can be regulated from one of the twoyarn tension seesaws. This makes a second special gearing unnecessaryand assures at the same time that the oscillation ranges of the two yarntension seesaws are always equal and the spring acting between theseesaws essentially maintains its length and tension.

The invention is explained in more detail in connection with the drawingwhich is a schematic perspective view showing the essential parts of atwo-needle bed Raschel machine.

A machine frame, not shown, supports two turning front and rear warpbeams 1 and 2, from which sets of warp yarns 3 and 4, indicated by onethread each, are drawn and pass over tension seesaws 5 and 6. The frontand rear sets of warp yarns 3, 4 are fed to the needle beds by yarnguides 7 and 8 which are carried on guide supports 11, equipped with forinstance six guide rods and pivotally mounted on a guide support shaft9. Swinging oscillation is imparted to the yarn guides 7 and 8 in theconventional manner by a connector rod .10. By swinging the guidesupports '11 and by the longitudinal movement of the guide rods in acertain rhythm, timed to the alternate raising and lowering of front endrear latch needles 12 and 13, stitches are alternatively made on thefront and back rows of the latch needles, as it is commonly known.

In order to provide the yarn length necessary for forming the courses ofstitches, the warp beams 1 and 2 are positively driven from the mainshaft 14 and through a special gearing 15. The special gearing 15 is inthe form of a variable speed drive which is driven from the main shaft14 by means of a chain drive 16. The output drive shaft 17 of thevariable speed gearing =15 drives a transmitting shaft 21 through a setof change gears 18, 19, and 20. A chain sprocket 22 is fixed on theshaft 21 and drives a chain 23 which passes over a sprocket 25 fixed onthe end of a shaft 24 on the warp beam 1. The end of the shaft 24 isalso provided with a gear 26 meshing with an equally sized gear 27 fixedon a reversing shaft 28. The drive of this reversing shaft is connectedto the warp beam 2 through a set of equally sized chain sprockets 29, 30over which a sprocket chain 31 passes.

Because of the equal dimensions of the pair of gears 26, 27 and the pairof chain sprockets 29, 30, the rotating speeds of the warp beams 1, 2,running in opposite directions, are always the same. The yarn tensionseesaws 5 and 6 are located on and fixedly connected to shafts 32 and33. Collars 36 and 37 are provided with respective upstanding levers 34and 35, and the collars are locked to the shafts with screws 38 and 39so that their circumferential positions can be adjusted. The levers 34and are provided with respective spring supports 42 and 43 which arefastened to them with screws and 41 in a similar way. Between thesesupports the tension spring 44 is suspended, 'which gives the yarntension seesaws 5 and 6 the back motion momentum acting against the pullof the sets of warp yarns 3 and 4.

Locked to the seesaw shaft 33 are further, at an angle to each other,two cam levers 45 and 46, acting on limit switches 47 and 48 which aresolidly attached to the frame. From the limit switches 47 and 48, wires49 and 50 go to a time relay 51 which is connected to the power supply52 of a reversible control motor 53 for the operating variable speeddrive 15. Two worm gear drives 54 and 55 with a connecting shaft 56create a considerable reduction between the speed of a driving shaft 57of the control motor 53 and an adjusting shaft 58 of the variable speeddrive 15.

The angle formed by the cam levers 45 and 46 is chosen large enough sothat the levers can oscillate freely between the limit switches with anormal oscillating movement of the seesaw 6, which is, due to the equalyarn consumption and the equal yarn feed, the same as that of seesaw 5.As long as the yard feed corresponds to the yarn consumption, this rangeof oscillation is maintained. But, if the rate of yarn feed deviatesfrom the rate of yarn consumption, which is for instance the usual casewhen the effective diameter of the warp beam is reduced, then one of thelimit switches 47, 48 is actuated by the corresponding cam lever 45, 46,energizing the control motor 53 through the time relay 51 whichmaintains the impulse for a time that is adjustable by a regulating knob59. The amount of rotation of the control motor 53 is such that the yarnfeeding speed is adjusted accordingly by adjustment of the variablespeed drive 15.

AS shown in the drawing, the warp threads 3 and 4 pass by on differentsides of the guide support shaft 9 and to the respective yarn guides 7and 8. During an oscillation movement of the guile support 11 toward therear, to the left in the drawing, a pulling force is exerted on thefront set of warp threads 3 which turns the yarn tension seesaw 5 in aclockwise direction. At the same time, the pull on the rear set of warpthreads 4 is reduced, whereby the yarn tension seesaw 6, actuated by thetension spring 44- also turns in a clockwise direction. When the guidesupports 11 and the yarn guides swing toward the front, to the right inthe drawing, the yarn tension seesaws 5 and 6 are turned accordingly inan opposite direction. By swinging the yarn tension seesaws 5 and 6 eachin the same direction, the length of the tension spring 44 remainsessentially the same and its potential energy practically does notchange. The result of this is a consider- 4 ably smoother oscillatingmovement of the yarn tension seesaws 5 and 6 which produces aconsiderably more even stitch structure in the knitted fabric.

In the drawing and specification there has been set forth a preferredembodiment of the invention and although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation. I claim: 1. A yarn tension control apparatus fortwo-needle bed fiat warp knitting machines, especially Raschel machines,having at least front and rear sets of warp yarns, yarn guides swingingback and forth across said needle beds, and a guide support shaftsupporting said yarn guides, said yarn tension control apparatuscomprising (a) front and rear yarn tension seesaws each includingspaced-apart tension rods with the respective front and rear sets ofwarp yarns passing under and over said tension rods and urging saidtension seesaws in one direction, and (b) common tension spring meansconnecting said front and rear tension seesaws and urging the same inthe other direction and against the pull of the sets of warp yarns. 2. Ayarn tension control apparatus according to claim- 1 wherein said commontension spring means comprises a single tension spring, and including apair of upstanding levers connected at their lower ends to said frontand rear tension seesaws, and means for connecting opposite ends of saidtension spring to said upstanding levers of said corresponding yarntension seesaws.

3. A yarn tension control apparatus according to claim 2 wherein saidspring connecting means is supported for longitudinal adjustment on saidupstanding levers to thereby vary the eifective length of said levers.

4. A yarn tension control apparatus according to claim 2 including meansconnecting the lower ends of said upstanding levers to saidcorresponding tension seesaws for angular adjustment therewith.

5. A yarn tension control apparatus according to claim 1 wherein saidknitting machine includes front and rear warp beams, and positive warpyarn feeding means for normally rotating said warp beams at a givenrate, and wherein said tension control apparatus includes control meansoperatively associated with one of said tension seesaws for varying thespeed of rotation of said warp beams.

6. A yarn tension control apparatus according to claim 5 wherein saidpositive warp yarn feeding means includes a variable speed drive unithaving an output drive shaft drivingly connected to said warp beams, andwherein said control means includes a pair of control levers connectedto one of said tension seesaws, a pair of limit switches operable bysaid corresponding control levers in response to abnormal movement ofsaid tension seesaw, a control motor drivingly connected to saidvariable speed drive unit and operable to change the rotational speed ofsaid warp beams, and a time delay relay unit interposed between saidlimit switches and said control motor whereby operation of said controlmotor is dependent upon actuation of one of said limit switches for apredetermined period.

References Cited UNITED STATES PATENTS 1,318,625 10/ 1919 Walther 66872,521,218 9/1950 Hepp 6686 2,598,540 5/1952 Henry 66--86 FOREIGN PATENTS134,360 11/1919 Great Britain 6687 6403020 5 1965 Netherlands 6686ROBERT R. MACKEY, Primary Examiner U.S. Cl. X.R.

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